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Hardness of water

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mg CaO/l
mg CaCO3/l
mg Ca2+/l
mg Mg2+/l

Rounding: significant digits.
Decimal sign:

Hardness of water is a measure for the content of calcium and magnesium in water. The small contribution of magnesium usually is expressed as calcium as in the degrees of hardness (at the top) and the concentrations of Ca2+, CaO and CaCO3 (at the bottom). Unfortunately, the classification of the degrees of hardness to water quality (soft, slightly hard, hard, very hard) is different in many countries.

Usage: Type the value to convert into the field, behind which you find the unit. Click on any empty space in the window or on the "calculate" button. Read the result in the other fields. Use the "reset" button to reset your calculation. Move the mouse over a unit or click on it to read its full name.

Example: A mineral water contains 140 mg Ca2+/l and 30 mg Mg2+/l. What is its degree of hardness? You have to calculate twice. At first, type "140" into the field behind which "mg Ca2+/l" is written. Click on any empty space in the window or on the "calculate" button. Read the result for calcium in the other fields (e.g. English degree of hardness: 24.5 °e or 3.49 mmol/l). For the calculation of the magnesium type "30" into the field in front of "mg Mg2+/l". After another click you see the result for magnesium (e.g. English degree of hardness: 8.7 °e or 1.23 mmol/l). You have to add both results to receive the total hardness, e.g. English degree of hardness: 33.2 °e or 4.72 mmol/l.

- Please note the remarks about the representation of numbers..
- There is no warranty for the calculation. Cactus2000 is not responsible for damage of any kind caused by wrong results.
- Please send an email if you have suggestions or if you would like to see more conversions to be included.

© Bernd Krüger, 14.07.2004, 18.08.2016, 11.08.2018

Bernd Krüger, 2022